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Pt Electrocatalyst Supported on a 3D-Nanoporous Carbon Shows a High Performance in a High-Temperature Polymer Electrolyte Fuel Cell
We have already reported that poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI) is an efficient dispersant for carbon supporting materials and provides the anchor sites for the Pt-nanoparticles (NPs) as well as creating the so-called three-phase boundary structure[1-7].
In this paper, we used a 3D nanoporous carbon (NanoPC) with a high specific surface area of 1,037 m2/g as a carbon support for high-temperature polymer electrolyte fuel cell, and fabricated an electrocatalyst (NanoPC/PyPBI/Pt) having platinum nanoparticles of ca. ~2.2 nm diameter deposited on the NanoPC that was wrapped by poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI). Even after 10,000 start-up/shutdown cycles in the range of 1.0 to 1.5 V vs. RHE, the NanoPC/PyPBI/Pt showed almost no loss in electrochemical surface area (ECSA), which was much higher durability than those of a CB/PyPBI/Pt (~32%-loss), in which conventional CB was used in place of the NanoPC, and conventional CB/Pt (~46%-loss).
FC performance of the assembled MEAs was evaluated at 120 ºC without any external humidification using a computer-controlled fuel cell test system. The polarization and the power density curves were measured under the atmospheric pressure by flowing dry hydrogen (flow rate; 100 mL/min) and dry air (flow rate; 200 mL/min) at the anode and the cathode, respectively.
The power density of the NanoPC/PyPBI/Pt was 342 mW/cm2, which was higher than those of the CB/PyPBI/Pt (183 mW/cm2) and CB/Pt (115 mW/cm2).
The present study provides useful information for the preparation of an electrocatalyst with a high durability and performance in high temperature PEFCs.
References
[1] N. Nakashima et al., Small 2009, 5, 735-740.
[2] N. Nakashima et al., J. Mater. Chem. 2011, 21, 1187-1190.
[3] N. Nakashima et al, Scientific Reports, 2013, 3, article no. 1764.
[4] N. Nakashima et al.,, ChemCatChem, 2014, 6, 567-571.
[5] N. Nakashima et al, Scientific Reports, 2014, 4, article no.6295.
[6] N. Nakashima et al., ChemPlusChem, 2014, 79, 400-405.
[7] Nakashima et al., N., J. Mater. Chem. A 2014, 2, 18875-18880.